Private Session Initiation Protocol Extension for Access Network Information
This mechanism is useful in SIP networks that provide layer 2/layer 3 connectivity through different access technologies. This document defines the private SIP extension header P-Access- Network-Info. SIP User Agents may use this header to relay information about the access technology to serving proxies in their home network. The serving proxy may then use this information to optimize services for the UA. For example, a 3GPP terminal uses this header to pass information about the access network such as radio access technology and cell ID to its home service provider.